I'd recommend you go ahead and answer. What you think is 50% of an answer may be 100% (or it may be 5%) -- no one will ever know unless you post. Failure should not be avoided. If you're on the right track, actively participating in the discussion is great. If you're on the wrong track, getting off that track early is probably best. I've had a few 'oh crap, what was I thinking' posts -- it's no big deal.